The present invention is broadly concerned with apparatuses for raising and supporting a shallow footing or foundation that has settled due to inadequate compaction of soil and other fill material due to erosion, soil consolidation, dehydration, or other causes. Various piering systems are currently in use for this purpose, and utilize piers of varying configuration and materials including wood, concrete, reinforced concrete, steel pipe, and steel bar stock. A pier is installed underneath or adjacent to a failed footing, and then the load of the footing is transferred to the installed pier by a bracket or load transfer device that is attached to the footing.
This invention deals specifically with a method and apparatus to be used for the installation of pipe piers. In the current art, a pipe pier is advanced into the ground using hydraulic driving cylinders, such as jacks, until a predetermined resistance against the pier is met. The pier is then terminated at an elevation that will allow a foundation load to be transferred to it via a bracket or load transfer mechanism connected to the foundation.
Pipe pier installation apparatuses utilizing either single or dual cylinder assemblies are typically used, whereby pier sections are added, section by section, as the pier is advanced into the ground. The depth to which a pier can be advanced is dictated by soil conditions, the driving force of the hydraulic cylinder(s), and the overall strength of the installation assembly.
Single cylinder installation assemblies push piers into the ground, with the piston rod pushing directly on top of the pier, while dual cylinder assemblies are typically inverted, utilizing a reaction to their driving force to pull the pier. One drawback of the single cylinder system is driving force. To develop enough driving force to push piers through dense soils, a single cylinder will either require a prohibitively large diameter, or an additional strength requirement to accept higher hydraulic pressures. The larger diameter cylinder becomes more awkward to handle in the field, and more prone to leakage. The use of high-pressure cylinders increases weight, which again makes the apparatus more cumbersome in the field, and requires larger and costlier hydraulic motors. Another shortfall of the single cylinder, push pier apparatuses currently in use is that they limit the length of pier sections that can be driven. For a single cylinder to be used in driving a pier, it must be concentrically positioned above the pier. This limits pier section lengths to the height inside the apparatus less the space taken up by the mounted cylinder, which impedes installation by requiring the constant insertion and removal of spacers.
Dual cylinder assemblies are more frequently used, as they resolve many of the problems attendant with single cylinder systems. The dual cylinders straddle the pier sections, and thus the pier sections are not limited in length by the available distance above the top of the pier within the installation assembly. Present art pertaining to dual cylinder assemblies often utilizes inverted cylinders that pull the pier into the ground as piston rods are retracted into the cylinders. In this arrangement, the pressurized cylinder chambers used in driving the pier contain the piston rods. As hydraulic fluid is pumped into the cylinders, it cannot act against the entire surface area of the pistons, as some of the available area is taken up by the piston rods. The chambers absent of the piston rods are pressurized during the backstroke, to position the apparatus for the next advancement. The cylinders are therefore not being used in their most effective manner when inverted.
Direct drive power cylinders are employed in the prior art whereby their full hydraulic capacity is used when driving piers. While this is the most efficient manner for driving piers, the assembly hardware for installing the power cylinders can be extremely heavy and unwieldy in the field. The efficiency of workers who must install the apparatus to the piers and supported foundation must be taken into consideration; a lighter power cylinder assembly would lead to faster installations, while causing less fatigue and injuries to the worker. It would be advantageous to have an apparatus for easily and quickly mounting a power cylinder to an assembly for driving a pier into the ground adjacent a footing to be supported.
The present invention utilizes a cylinder mounting beam assembly that allows hydraulic cylinders to be positioned within the installation apparatus such that they can utilize their full capacity when driving piers. The cylinder mounting beam assembly is adapted to be used in connection with currently existing pier driving apparatuses of the type which provide for placement of two offset hydraulic cylinders that straddle the pier. The pistons of the hydraulic cylinders are connected to a clamping member which grips the pier for urging the pier into the ground. This type of pier driving apparatus further has driving arm members, against which the power cylinders are indirectly braced, which engage the footing, such as through a bracket or other load transfer mechanism placed underneath the footing.
The invention comprises a planar pier retaining member having a central opening for receiving the pier and has connection points for attachment to the driving arm members of the pier driving apparatus. Top ends of the hydraulic cylinders are connected to the bottom side of the planar pier retaining member with the piston rod ends of the hydraulic cylinders depending downwardly to connect with the clamping members that engage the pier to be driven. In this arrangement, the hydraulic cylinders are able to drive the pier utilizing the push stroke of the piston rod instead of the back stroke. In one embodiment of the invention, the pier retaining member is comprised of plate members capable of disassembly, so that the mounting beam assembly may be broken down into separate components. This arrangement allows the pier driving process of the footing supporting operation to proceed much more efficiently in that the mounting beam assembly is of a reduced weight, making it easier for the worker to lift, and also because installation of the mounting beam assembly can be done laterally around the pier rather than sliding down over the top of the pier. Another embodiment features a unitary planar pier retaining member having an opening at its lateral side to receive the pier.
It is therefore an object of the invention to provide a hydraulic cylinder mounting beam assembly which can be used in connection with existing foundation supporting bracket assemblies. It is a further object of the invention to provide a hydraulic cylinder mounting beam assembly which is capable of mounting the hydraulic cylinders in such a way that the direct power stroke of the piston rods is utilized. It is still further an object of this invention to provide an embodiment of a hydraulic cylinder mounting beam assembly which is capable of disassembly into component parts. It is still further an object of this invention to provide a mounting beam assembly that permits lateral installation onto the pier.
The above features are objects of this invention. Further objects will appear in the detailed description which follows and will be otherwise apparent to those skilled in the art.
For purpose of illustration of this invention preferred embodiments are shown and described hereinbelow in the accompanying drawing. It is to be understood that this is for the purpose of example only and that the invention is not limited thereto.